Italian meringue buttercream

Wipe the mixing bowl with a little lemon or vinegar so no fat remains.

Separate the eggs one at a time, putting each white into the mixer bowl; save the yolks.

In a small pot, moisten the sugar with the water and set over medium-low heat.

Add the cream of tartar and salt to the whites and whip until light and frothy.

Drizzle in the meringue sugar very slowly so it dissolves, then beat on high to soft peaks.

Heat the syrup to 235 to 240F, the soft-ball stage: a drop in cold water should form a soft ball, not a stream (too cool) or a hard ball (too hot).

With the mixer running at high speed, drizzle the hot syrup in toward the centre, not down the side of the bowl.

Keep mixing on medium-high until the meringue is almost room temperature; pack the outside of the bowl with frozen vegetables or ice to speed cooling.

Butter should yield when pressed; if too cold, give it a few seconds at half power in the microwave.

Switch to the paddle and add the butter a tablespoon at a time on lower speed; scrape the bowl. If it turns soupy, keep mixing, or chill the bowl about 5 minutes and mix again.

Mix until the butter is fully incorporated and the buttercream is silky.

Flavour at the very end, to taste, and use it at once: meringue frostings lose their consistency within about 10 minutes.

Variation: fold about half a cup of melted, cooled bittersweet chocolate into part of the batch for chocolate Italian meringue buttercream.

Variation: use browned butter, cooked in a small pot over low heat until a deeper caramel colour.

Store airtight in the fridge for a week or the freezer for a month; thaw in the fridge overnight, then on the counter to room temperature, never in the microwave.

Rewhip about 30 seconds after thawing or standing to restore the silky texture, then pipe.